Fluorination of trifluorotrichloro-propene



Patented Feb. 23, 1954 FLUORINATION F TRIFLUORO- TRICHLORO-PROPENE' HansB. Gottlieb, Glassboro, N. 3., and J o'seph D.

Park, Boulder, 0010., assignors to El. duPont de "Nemours& Company,Wilmington, DeL, a

corporation of Delaware NoDrawing, Application April 29, 1949,

Serial No. 90,566

CFbCClFCC1F2 I are useful as heat transfer media, solvents, re-

action media, dielectric materials and as intermediates in themanufacture of refrigerants. However, they are particularly valuable asintermediates for the manufacture ofand CF3CF:CF2 by dechlorinationwhich latter compounds may be polymerized .to form valuable polymericmaterials. Also,

may be readily converted to CF3-CClF-CC1F2 by treatment with HF by wellknown methods.

Prior methods for adding fluorine to the double bonds of olefiniccompounds have certain. disadvantages. The use of PbOz or C0203 and HFrequire the use of high pressures, refrigeration,

liquid phase and limited batch processes and are difiicult to controland result in relatively low yield.

McBee et al., in Industrial and'Engineering Chemistry, vol. 39, No. 3,March 1947, pages 310' to 313, disclose thatpolychloropolyfluoroheptenes can be fluorinated by passing vapors.thereof over COFx. They found that chlorine was replaced by fiuorine atthe lower temperatures and that high temperatures of about 350 C. to 400C. were required to obtain substantial saturation of the double bonds byfluorine,:. at the same time obtaining substantially completereplacement of chlorine by fluorine.

It is an object of the present invention taprovide'a simple, economicaland readilycontrolled process for adding fluorine to'the'double 'bond of'1: 1: 1-trifluoro-2 :3 :3-trichloro-2-propene and obtain technicallyvaluable products in improved yields." Another object is to provide sucha method which avoids substitution of iaematerial proportion of chlorineby fluorine, i.e., over-fluorination.v A'further object .is to providesuch a process. which. produces. 2:3:3 -trichloropenta-- Still anappear*hereinafter.

2Q; The above and other objects :tmay' be accomplished inaccordance-with our invention which comprises passing a. mixture-ofvapors of 1:1:1-

trifiuoro-2 :313-trichloro-2-propene and an inert gas, which mixture:contains'from'about 3%. to about 50% by weight of.the-trifluoro-etrichloropropene, over powdered'coFs heatedat a.temperature of from about 50 C. to about:150? C. at a contact time offrom about 1 to about 10 minutes while stirringthe powdered COFstocontinuously expose fresh surfaces thereof to the mixture of gases'andtheniseparating' the products.

We have found that,'.by,such1 process, .we can obtain high yields of2z3'z'3- trichloropentafluoropropane and 2:3-dichloro'hexafluoropropaneas the main products and. avoid-:the production of substantial amountsof more high1y fiuorinated products and polymers. Such process avoidsthe objectionable features of theprior processes and is simple andeconomical. to operate; The reactions take place smoothly and theprocess is readily controlled. The'yield of saturated products is muchhigher than has beenJobtained by bed of the. solid fluorinating agentand' provided with means for agitating the solid fiuorinating agent, andtraps or condensers for collecting the products of the reaction. Thereactor for use in our process may suitably be made of steel or of analloy having the composition -70%" Ni, 25-35%Cu, l-3%Fe,-,0.25'-2.0%--Mn, 0-.02-'1.5% Si and. 0.3-0.5 C. and which isgenerally-known to the art as Monel.

The process should beicarriednout at temperatures of from about50 C. toabout150 C. At temperatures material-1y below 50- C.;-.the reactiontends to'be too slow-and the yields too low to be practicable. Attemperatures materially above 150 0., there is a tendency toward overfluorination and hence the production of compounds not desired at theexpense of the desired compounds. Within the range of 50 C. to 150 C.,the lower temperatures favor the conversion to CF3-CClF-CC12F, whereas,the higher temperatures and longer contact times favor the conversion.to .CF3-CC1FCC1F2. Generally, temperatures of from about 50 C. to aboutC. produce-CFb-CClF-CChF as the main product 3 with optimum conversionsat temperatures of from 50 C. to about 80 C. At temperatures above 115C., CF3CClF-CC1F2 will usually constitute the main product, particularlywith 4 CFs-CCI CCh, could be reconverted to CoFs with elemental fluorinein the same reactor.

An evaporator, kept at 25 C., was charged with 107 g. CF3CC1:CC12 (B. P.883 0.).

the longer contact times, with optimum conver- 5 This amount oftrifluoroetrichloro-propene was sions at about 150 C. evaporated, overthe course of 8 hours, by a our- The contact times may vary from about 1minrent of dry nitrogen bubbling through the proute to about 10 minutes.At contact times mapene at the rate of 32 liters per hour. Thereterially below 1 minute, the yields will usually sulting mixturecontained about 1 part of be too low to be practicable. With contacttimes 10 c1i cc1=ccl materially above 10 minutes, there is a tendencyfor over fluorination with decrease in yield of to parts of mtrogenwelght or about 35'7% the desired products. Optimum yields of the de-Durmg these 8 3 the sired products are generally obtained with conwaspassed through the cobamc mfiuo' tact times of from about 3 minutes toabout 7 15 ride reactor heated at a controlled temperature minutes ofapproximately 60 C. Contact time was about The Vapors of thetrifiuormtrichlom propene 3.6 minutes, since it took this time tocompletely must be diluted with an inert gas for control of replica thegas m t frge Space the reactor the temperatures and the reaction.Suitable (2 liters) by mflowmg gas-mlgture' The inert gases arenitrogen, anhydrous hydrogen prompts of reactwn W stnubbed .Wlth aqugousfluoride, and the saturated fluorocarbons which alkalme solutmn (triedWlth cammed. f? are gaseous at the temperatures employed. The sltlfatecondense? traps 9 i hqmd term fiuorocarbons" is used in its strict sensemtrogen Fm framonateq by dlstluauon. to mean compounds consisting offluorine and h? chlef product emailed g the dlfiuoro' carbon.Representative fluorocarbons are: tetra- 5 afddmon compound or q?fluoromethane, hexafiuoroethane, octafluoroprograms (56% g? fii g tpane, decafluorobutane, octafluorocyclobutane, 25333222 5; 6ggifilllorocyclopentane, and dodecafiuorocyclo a 1 t g ffig gg 51 0could be For the purpose of controlling the temperae m 0 an cpnversmn'respec' tures and the reaction and causing the reaction g f L FQ ZTlguseful as to take place smoothly, the concentration of the {t lea: Ionme and dle ectrifluoro trichloro pmpene m the gaseous tile material.Altogether, conversion to techniture should not be greater than about50% by Cally Saul produets amounted to Weight. Gaseous mixturescontaining material- EXAMPLE II ly less than 3% by weight of thetrifiuoro- The cobaltic trifiuoride reactor, used in Exchloro-propeneare inefiicient. Usually, the gaseample I, Wasagain emp1oyed Itcontained the 0115 mixture contain from about 3% to about 331113 amountof C0F The same trifluQro-tri.. by Of thB triiluoro-trichloro-propenehloro propene ra s emplayed and th method Wlth Optlmum results belngObtamed at concen- 49 of isolating the products of reaction was also thetrafiions of from about 25% t0 about by same as in Example 1'.Conditions of tempera- Welghtture and contact time were, however,different O y, the P s Will be carried out at from those in Example I.The evaporator was substantially atmospheric pressures, i. e.,atpreskept at 5 C to 4 C, and 123,7 grams msures Of from about 1 to about2 atmospheres fluorg trjchloro prgpene were evaporated in it inabsolute. Higher and lower pressures can be emt course f 12 hours, Thespeed of dry nitro- D y but usually Without Substantial advangenemployed for this evaporation measured tags For example, the pressuresmay be varied only 16 liters per hour. This resulted in a mixbetweenabout Ar atmosphere to about 5 atmosture of about 1 part of thetrifluoro-trichloro- D e absolutepropene to 2.8 parts of nitrogen byweight or In order to more clearly illustrate our invenabout 3 of c c 1:1 The temperation, preferred modes of carrying the Same into ture of thecobaltic trifluoride reactor, through efiec and the advantageous resultsto be which the mixture of nitrogen and trifiuoro-trim ed t ere y, thefollowing exa pl s a e g ven: chloro-propene was passed during said 12hours, was kept at C. The contact time was about EXAMPLEI 7.2 minutes.Stronger fluorination occurred. The cobaltic trifluoride reactor was apipe, Less than 4.6 of the original propene was conmade of Monel, 4inches in diameter and 32 verted to the difluoro-acldition compound,49.6% inches long and contained 3600 grams of powwas converted toCF3CC1F-CC1F2 (B. P. 34.7 dered COF'3. The powder was stirred so as to 0C.) and 10% to CF3CC1FCF3 (B. P. 2 C.). continuously expose large freshsurfaces to the Altogether, conversion to technically useful vaporspassing through the pipe, and from this products amounted to about 64%.good contact resulted between the fiuorination The effect of varying thetemperatures, contact agent and the vapor of the CF3-CC1=CC12. times andconcentration of the gases will be more The C0F2, formed in thefiuorination of the 5 readily apparent from the following table:

Table Contact Nitrogen, Percent conversion of CFi-OCl=CClz to Tcmp., 0.time, liters/ CFz-CC!F-CC12F CF;CClF-CCIF:

3.6 32 56 13.8 3.6 22 so as 1.2 16 35.1 24.6 7.2 16 4.e 49.6 3.6 32 21.536.8-

In the course of the work illustrated by the examples and the table, nodimers or other polymeric materials were detected. If any were found inonly small amounts, probably less than of the reaction products.

It will be understood that the preceding examples and table are givenfor illustrative purposes solely and that our invention is not limitedto the specific embodiments disclosed therein. The temperatures, contacttimes, concentrations and other conditions may be varied Within thelimits hereinbefore set forth and such modifications are embraced withinthe scope of our invention. Likewise, the apparatus, methods ofpreparing the gaseous mixtures, and the methods of collecting, purifyingand separating the reaction products may be widely varied as is Wellknown to those skilled in the art without departing from the spirit orscope of our invention.

It will be apparent that we have provided a simple, economical,efficient and readily controlled process for producing the very valuablecompounds 2:3:3 trichloropentafluoropropane and 23-dichlorohexafluoropropane in greatly improved yields and have avoidedthe objectionable features of the processes of the prior art.Accordingly, it is apparent that our invention constitutes a valuablecontribution and advance in the art.

We claim:

1. The process for preparing at least one of 2 33-trichloropentafluoropropane and 2 3-dichlorohexafluoropropane whichcomprises passing a mixture of vapors of 1:1:1-trifluoro-2:3:3-trichloro-2-propene and an inert gas, the mixture containing from about3% to about 50% by weight of the trifluoro-trichloro-propene, overpowdered COFs heated at a temperature of from about 50 C. to about 150C. at a contact time of from about 1 to about minutes, while stirringthe powdered CoFb to continuously expose fresh surfaces thereof to themixture of gases and then separating the products.

2. The process for preparing at least one of 2 33-trichloropentafiuoropropane and 2 3-dichlorohexafluoropropane whichcomprises passing a mixture of vapors of 1:1:1-trifiuoro-2z3z3-trichloro-2-propene and an inert gas, the mixture containing from about3% to about 36% by weight of the trifluoro-trichloro-propene, overpowdered CoFa heated at a temperature of from about 50 C. to about 150C. at a contact time of from about 1 to about 10 minutes, while stirringthe powdered COFs to continuously expose fresh surfaces thereof to themixture of gases and then separating the products.

3. The process for preparing at least one of 2 3:3-trichloropentafluoropropane and 2 3-dichlorohexafluoropropane whichcomprises passing a mixture of vapors of 1:1:1-trifluoro-2:3:3-trichloro-Z-propene and an inert gas, the mixture containing from about3% to about 36% by weight of the trifluoro-trichloro-propene, overpowdered COF3 heated at a temperature of from about 50 C. to about 150C. at a contact time of from about 3 to about 7 minutes, while stirringthe powdered COF's to continuously expose fresh surfaces thereof to themixture of gases and then separating the products.

4. The process for preparing at least one of 2:3:3-trichloropentafluoropropane and 2 3-dichlorohexafluoropropane whichcomprises passing a mixture of vapors of 1:1:1-trifiuoro-2:3:3-trichloro-Z-propene and an inert gas, the mixture containing from about25% to about 36% by weight of the trifiuoro-trichloro-propene, overpowdered COF3 heated at a temperature of from about 50 C. to about 150C. at a contact time of from about 3 to about 7 minutes, while stirringthe powdered COFs to continuously expose fresh surfaces thereof to themixture of gases and then separating the products.

5. The process for preparing at least one of 2 33-trichloropentafluoropropane and 2 3-dichlorohexafluoropropane whichcomprises passing a mixture of vapors of 1:1:1-trifluoro-2:3:3-trichloro-z-propene and an inert gas, the mixture containing from about3% to about 50% by weight of the trifluoro-trlchloro-propene, overpowdered CoF3 heated at a temperature of from about 50 C. to about 115C. at a contact time of from about 1 to about 10 minutes, while stirringthe powdered CoFa to continuously expose fresh surfaces thereof to themixture of gases and then separating the products.

6. The process for preparing at least one of 2 33trichloropentafluoropropane and 2 3-dichlorohexafluoropropane whichcomprises passing a mixture of vapors of 1:1:1-trifluoro-2:3:3-trichloro-2-propene and an inert gas, the mixture containing from about3% to about 36% by weight of the trifluoro-trichloro-propene, overpowdered CoF3 heated at a temperature of from about 50 C. to about 115C. at a contact time of from about 1 to about 10 minutes, while stirringthe powdered CoF3 tocontinuously expose fresh surfaces thereof to themixture of gases and. then separating the products.

7. The process for perparing at least one of 2 :33-trichloropentafluoropropane and 2 3-dichlorohexafluoropropane whichcomprises passing a mixture of vapors of 1:1:1-trifluoro-2:3:3-trichloro-2-propene and an inert gas, the mixture containing from about25% to about 36% by weight of the trifluoro-trichloro-propene, overpowdered COFs heated at a temperature of from about 50 C. to about 11 C.at a contact time of from about 3 to about 7 minutes, while stirring thepowdered CoF3 to continuously expose fresh surfaces thereof to themixture of gases and then separating the products.

8. The process for preparing at least one of 2 :33-trichloropentafluoropropane and 2 3-dichlorohexafluoropropane whichcomprises passing a mixture of vapors of 1:1:1-trifiuoro-2:3:3-trichloro-2-propene and an inert gas, the mixture containing from about25% to about 36% by weight of the trifiuoro-trichloro-propene, overpowdered COFs heated at a temperature of from about 50 C. to about C. ata contact time of from about 3 to about 7 minutes, while stirring thepowdered CoFs to continuously expose fresh surfaces thereof to themixture of gases and then separating the products.

HANS B. GOTTLIEB. JOSEPH D. PARK.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,436,357 Gochenour et al. Feb. 17, 1948 2,541,190 BenningFeb. 13, 1951 2,554,857 Gochenour May 29, 1951 FOREIGN PATENTS NumberCountry Date 559,080 Great Britain Feb. 3, 1944 OTHER REFERENCES McBeeet al.: Ind. and Eng. Chem, vol. 39, No. 3, pages 310-312, March 1947.

1. THE PROCESS FOR PREPARING AT LEAST ONE OF 2:3:3-TRICHLOROPENTAFLUOROPROPANE AND 2:3-DICHLOROHEXAFLUOROPROPANE WHICH COMPRISES PASSING A MIXTURE OF VAPORS OF 1:1:1-TRIFLUORO-2:3:3TRICHLORO-2-PROPENE AND AN INERT GAS, THE MIXTURE CONTAINING FROM ABOUT 3% TO ABOUT 50% BY WEIGHT OF THE TRIFLUORO-TRICHLORO-PRPENE, OVER POWDERED COF3 HEATED AT A TEMPERATURE OF FROM ABOUT 50* C. TO ABOUT 150* C. AT A CONTACT TIME OF FROM ABOUT 1 TO ABOUT 10 MINUTES, WHILE STIRRING THE POWDERED COF3 TO CONTINUOUSLY EXPOSE FRESH SURFACES THEREOF TO THE MIXTURE OF GASES AND THEN SEPARATING THE PRODUCTS. 